The Adobe® Pixel Bender™ technology delivers a common image and video processing infrastructure which provides automatic runtime optimization on heterogeneous hardware. You can use the Pixel Bender kernel language to implement image processing algorithms (filters or effects) in a hardware-independent manner. The Pixel Bender graph language is an XML-based language for combining individual pixel-processing operations (kernels) into more complex Pixel Bender filters. (adobe)

Sounds good? Pixel Bender also alows you to do audio / video processing, and even raw bytes procesing, both are incredibly fast when it comes to compare with ActionScript processing. Pixel Bender comes with its own SDK, but is not very handy. You should rather give a try to PBDT (Eclipse plug-in).

Worth to mention facts are: PB does not offer many tools to work with, there are just few methods, calculations and object types, but it seems to be enough to do all required data processing. Learning curve is extremely steep. Soon you get familiar with language, but to do some advanced stuff it will take a lot of effort. PB is supported by multiple Adobe applications.

When it comes to flash, another important thing is, you can run your processings asynchronously. Flash Player 10 is required. Once a Pixel Bender shader is available in ActionScript as a Shader object, it can be used in several ways:

Shader drawing fill: The shader defines the fill portion of a shape drawn using the drawing api

Blend mode: The shader defines the blend between two overlapping display objects

Filter: The shader defines a filter that modifies the appearance of visual content

Stand-alone shader processing: The shader processing runs without specifying the intended use of the output. The shader can optionally run in the background, with the result is available when the processing completes. This technique can be used to generate bitmap data and also to process non-visual data.